Bagmaking machine



Sept. 22, 1953 T. w. KELLER ET AL BAGMAKING MACHINE 8 Sheets-Sheet 1Original Filed March 25, 1949 \NN %NN QNN Mm FT r3 L N 0 NM A NQN NN QNSept. 22, 1953 T. w. KELLER AL BAGMAKING MACHINE 8 Sheets-Sheet 2Original Filed March 23, 1949 V 5 MN W W L/ ZLV w m f A V X nw J w M Rrm W P 1953 "r1 w. KELLER ET AL 2,652,879

BAGMAKING MACHINE Original Filed March 25, 1949 8 Sheets-Sheet 3 I NVENTORfi THEODORE n. KELLER BGELHARLES W. GA/PVl/V Sept. 22, 1953 T. w.KELLER ETAL BAGMAKING MACHINE m R 4 t m tE h K K4 Z j P M S O E 8 I W m.kw MM 1 %k -ww T 0 HQ vmw Original Filed March 23, 1949 Sept. 22, 1953'r. w. KELLER ETAL BAGMAKING MACHINE Original Filed March 25, 1949 8Sheets-Sheet 6 INVENTORS THEODQRE W KELLER BYGHARLES m GARV/IV 4M fiu KJaw- Sept. 22, 1953 T. w. KELLER ET AL BAGMAKING MACHINE Original FiledMarch 25, 1949 8 Sheets-Sheet 7 QNN MN MM U M W K 5 frzrezzzars.THEODORE W. KELLER Atiforzzegmb Sept. 22, 1953 T. w. KELLER EI'ALMBAGMAKING MACHINE 8 Sheets-Sheet 8 Original Filed March 23, 1949 [721622107'5. THEODOR' W KELL 6 Patented Sept. 22, 1953 UNITED STATESA'lTENT EFHCE Charles W.

Garvin, Omaha, N ebr.

Original application March 23, 1949, Serial No. 82,934. Divided and thisapplication June 19, 1951, Serial No. 240,768

23 Claims. 1

This invention relates to a machine for heat sealing multi-layerthermoplastic stock, and more particularly to a machine for fabricatingbags from tubular extruded thermoplastic stock.

Numerous recently developed thermoplastic materials are recognized to beexcellent packaging materials, especially for food, but are not readilyadaptable to fabrication into bags and the like by known machines. Heatsealing, for example, is commonly employed to process thermoplasticstool: into seamless bags. some materials, however, notably polyethyleneand polyvinylidene chloride, are difficult to handle and fabricatesatisfactorily by conventional heat sealing machines, because ofpronounced tendchoice to stick to heated machine elements, to deformwhen heated, and especially because of their sharply defined meltingpoints. The latter property necessitates rigid control of thetemperature and pressure employed in the heat sealing operation, toattain an effective seal without severing or otherwise damaging thematerial. In addition, polyethylene is a dielectric, so that electricalheating methods therefor are not feasible. The properties of thesematerials have heretofore limited their us to tedious and expensivemanually controlled heat sealing operations.

Polyethylene polyvinylidene chloride are commonly extruded in tubularform, and supplied as rolls of flattened tubular stock, wound on hollowcores. The flattened tubing is produced in various widths, ranging fromone inch to several feet, and wall thicknesses, ranging from .001 to.030 inch or more, and is furnished either with or without side tucks.in length from 100 yards to about 800 yards, depending on width andthickness. It is particularly to the automatic and continuousfabrication of the above-described tubular stock material into bags thatthe present invention'is directed.

The present machine is based on the concept of using preformed tubularstock of appropriate width and wall thickness for the type of bagdesired, intermittently feeding said stock from a suitable supply inmeasured and regulated bag tensioning the stock, transversely heatsealing the stock into integral bag lengths, and finally cutting offfinished bags by severing the stock adjacent the heat seals.

It is an object of the present invention to provide a novel and eficient apparatus for heat sealing multi-layer thermoplastic stockmaterial.

I is a further object of the present invention to provide a machine forcontinuously and auto- The rolls vary matically fabricating tubular intoseamless bags.

A further object of the invention is to provide a bag making machineemploying as starting material tubular thermoplastic stock of variouswidths and thicknesses, and adjustable to produce therefrom bags ofWidely variable length.

A particular object of the invention is to provide apparatus adapted touniformly and effectively heat seal multi-layer thermoplastic stock ofuneven thickness along the sealing line, or of different numbers oflayers along said line.

A further object is the provision of means to prevent sticking ofpolyethylene-type material to heated sealing elements in heat sealingoperations.

Other objects of the invention will be in part obvious and in partpointed out hereinafter.

The invention and the novel features may best be made clear from thefollowing description and the accompanying drawings, in which:

Figure 1 is a side elevation of a preferred embodiment of the presentinvention;

Figure 2 is a plan view of the machine of Figure 1, with parts brokenaway for clarity;

Figure 3 is an enlarged sectional plan view of the mechanism for drivingand coordinating the various component mechanisms of the machine;

Figures 4, 5 and 6 are enlarged views of the cams governing theoperation of the cutter, the heat sealer, and the sealer wipers,respectively;

Figure 7 is a detailed View of the feed roll d1'iving mechanism, takenon the line 7-1 of Figure 2;

Figure 8 is an enlarged sectional view of the feed roll driveoverrunning clutch, taken on the line 8-3 of Figure 7;

Figure 9 is a detailed view of the feed roll drive adjustment, takensubstantially on the line 9-9 of Figure 7;

Figure 10 is an elevational view of the twospeed differential mechanismfor the feed r011 drive, taken on the line lib-it of Figure 2;

Figure 11 is a sectional view taken along the line il-li of Figure 10;

Figure 12 is a plan view of the differential drive of Figure 10, showingdetails of the speed changing mechanism;

Figure 13 is an enlarged sectional elevation of the heat sealingmechanism and the associated wipers therefor, taken on the line !3l3 ofFigure 2;

Figure 14 is a section taken along the line l t-it of Figure 13;

Figure 15 is an enlarged sectional elevation of thermoplastic stock thestock length adjustment mechanism, taken on the line Iii-i5 of Figure 2;

Figure 16 is a section taken on of Figure Figure 17 is an enlargedsectional elevation of the stock guiding andcutting mechanism, taken onthe line ll-l'l of Figure 2;

Figure 18 is an enlarged detail view of the roll separating means forthe first feed roll pair, taken on the line l8-l8 of Figure 2;

Figure 19 is an enlarged detail view of the roll separating means forthe second feed roll pair, taken on the line I9l9 of Figure 2;

Figure 20 is a plan view of the table section broken away in Figure 2,showing the stock control bars thereon, and

Figure 21 is a circuit diagram of the electrical system. of theembodiment illustrated.

Referring to the drawings, particularly Figures l and 2, the preferredembodiment comprises a frame It, suitably mounted as on legs 5 i, whichmay be castered if desired, to permit shifting of the machine from placeto place. At one end of the frame a plurality of spindles i2 areremovably mounted in suitable bearings, each of the spindles carrying apair of adjustable positioning cones i3, adapted to position and alignthe hollow cores upon which rolls of the tubular stock 54 arecustomarily wound. For final alignment of the stock, the spindles aredesirably adjustable transversely of the frame, as by the screws i5engaging the spindle bearings and carrying the disc members it, by whichthe spindle end grooves El are engaged. The opposite ends of thespindles are slotted as at it, whereby they slidably engage the pins E9of the brake discs 20, whereby the brake discs are rotatable with thespindles to control the stock feed therefrom in a manner presently to bedescribed.

Stock rolls may be mounted on each of the spindles l2 and fed into themachine one at a time, each roll as it approaches exhaustion beingsealed or otherwise suitably connected to a new roll on the otherspindle, permitting the machine to operate substantially withoutinterruption for stock replenishment, and avoiding the necessity ofrethreading the machine with each roll of stock. Operated in thisfashion, the machine processes a single stock strip, and produces bagssingly. To produce a plurality of bags simultaneously, as may bedesirable in operating with narrow stock, stock rolls may be laterallyoffset relative to each other on the spindles, and the stock stripspassed through the machine side by side. The several feeding, sealingand cutting mechanisms function in the same manner whether operatingupon a single strip or upon a plurality of strips.

The spindles revolve in the direction shown by the arrow in Figure 1,and the tubular stock is drawn off along the path indicated by thedotted line, passing under the guide ro'ds 2| and then over the guideroll supported by the uprights 23 extending from the machine frame.Adjacent guide roll 22 the uprights support the pivot bearings 2 uponwhich the arms 25 are pivotally mounted, supporting at one end thereofthe swinging guide roll 26. From guide roll 22, the stock passes aroundthe guide roll 26, and thence over the fixed guide rolls of rods 21 to aposition immediately above the table section 28.

Coupled to the opposite end of one of the arms 25 is the push rod 29,engaged and urged upwardly by the enclosing spring 30. The thrust rod 32is operatively engaged by push rod 29 the line iii-l5 through thebellcrank 33, pivotally mounted on the frame of the machine. By means ofsprings 34 and levers 35, thrust rod 32 urges the brake blocks 36 intofrictional engagement with brake discs IS with variable pressure. As thestock is intermittently drawn from the feeding mechanism over the guiderods 21, the guide roll 26 is caused to swing upwardly, pivoting thearms 25 in the clockwise direction as shown in Figure 1, therebyeffecting through push rod 29 and thrust rod 32 a lessening of thepressure of brake blocks 36 on the brake discs l9, and permitting thespindles l2 to rotate more easily to let off stock. In this manner, theswinging guide roll 26 and the associated mechanism act not only toautomatically control the stock feed and maintain proper tension, butalso, primarily by means of the weight and swinging action of the arms25 and roll 26, to smooth out the inertia effect of the feedingoperation.

From the guide rods 21, the stock passes over table section 28, passingunder the control bars 31, and then successively through the first feedroll stand indicated generally as 38, the heat sealer 39, the secondfeed roll stand 40, and the cutter 42, into receiving tray 43. The feedrolls, the heat sealer and associated wiper mechanism, and the cutter,each described hereafter in detail, are all intermittently driven insuitably coordinated manner by a single source of motive power, such asthe motor 44. As shown, motor 44 depends from the plate 45, slidablyretained between the guide channels 46, which are rigidly secured to theframe of the machine. The internally threaded lug 41 extends from plate45 and is engaged by the threaded crank rod 48. Rotation of the crankrod 48 is effected by the handle 49, by means of which, it will beunderstood, the plate 45 and motor 44 may be displaced relative to theguide channels 46. The motor 44, by means of a conventional variablespeed pulley (not shown), drives belt 50 and the pulley 52, extendingfrom gear box 53 (see Figure 3) By this arrangement, the tension of thebelt 50 may be altered by relatively displacing the motor 44, therebychanging the effective pitch diameter of the variable speed pulleydriving the belt, and adjusting the rotational speed transmitted to thepulley 52. In place of this arrangement, a variable speed motor andsuitable controls therefor may be employed. Within gear box 53 thepulley 52 is operatively engaged through speed reducing gears to thedrive shaft 54.

Drive shaft 54 is the common driving element for the stock feedingmechanism, the heat sealer, the heat sealer wiper mechanism, and thecutter, all of which operate intermittently. All of the intermittentlyoperating component mechanisms being driven by a common shaft, propercoordination thereof is positively and simply effected. The stockfeeding mechanism will first be described, and comprises the slidecarrier 55, mounted at one end of drive shaft 54 and provided withsuitable ways 56, adapted to support and guide the slide member 51retained therebetween. Slide 51 is threadably engaged by the adjustingscrew 58, whereby it may be controllably displaced longitudinally of theslide carrier. The screw 58 is provided at one end thereof with the slot59, for rough adjustment of the slide, and at the opposite end thereofwith the star Wheel 50, for finer adjustment of the slide (see Figures 3and '7). By means of pin 62, the slide is pivotally connected in drivingrelationship to the rack 63, arranged to reciprocate within the gearcase 64, wherein the rack engages gear 65, keyed to the conventional oneway overrunning clutch indicated generally as 66 (Figure 8). Theoverrunning clutch transmits rotary motion of the gear 55 in onedirection only to the shaft 37, suitably journalled in the frame of themachine. It will be readily understood that by means of the slidecarrier 55, slide 57, rack 63, gear 65 and the overrunning clutch 6B,continuous rotation of the drive shaft 54 is converted into intermittentrotary movement of the shaft El.

By adjusting the slide 51 relative to the slide carrier 55, theoperative throw of rack 63 and the corresponding rotary movement ofshaft El occasioned by each revolution of the drive shaft 55 may bevaried as desired. When the machine is at rest, this may be accomplishedby the rotation of screw 58 by means of a suitable tool engaged to theslot 59 thereof. Means are also provided for adjustably positioning theslide 57 when the machine is in operation. As best shown in Figures 2, 7and 9, the path of the slide carrier is partially enclosed by thehousing 68, mounted on gear box 53. Arm 39, pivotally mounted in housing68, supports the downwardly depending adjusting pin Til, and iscontrolled by the rod 12 and handle 13 extending outwardly from the sideof the machine frame. By moving handle l3 to place pin H! in dotted lineposition A (Figure 9), it will be seen that each revolution of the slidecarrier brings star wheel as into engagement with adjusting pin it andeffects angular displacement of the star wheel and the associated screw58, thereby adjusting the position of the slide 5?. gressively as longas the adjusting pin remains in position A. By moving the pin Til to thedotted line position B, adjustment in the opposite direction iseffected. When no adjustment is required, the pin ii} is maintained inthe neutral position shown in full lines.

Each of the feed roll stands 33 and 68 supports a pair ofccntra-rotating feed rolls M, desirably surfaced with soft rubber orsimilar traction material, suitably journalled in said stands and urgedinto pressure contact by the springs 15 bearing on the ends of the upperfeed rolls. The feed roll pairs are interconnected, and driven in unisonin accordance with the intermittent rotation of shaft 67, whereby theyengage and ad- Vance the stock in step-by-step fashion. Referringparticularly to Figures 10, 11 and 12, the feed roll pairs are driventhrough the shaft 16, which extends outwardly from the lower feed rollof stand 38, and is operatively engaged to the shaft 6? by means of thedual ratio transmission mechanism indicated generally as ll.Transmission i'l comprises a small sprocket l8 and a larger sprocket l5mounted side by side on shaft Bl, each engaged by a chain 35. The chains86 also engage idler sprockets 82 and identical sprockets $3, pinned toshaft it. Each of sprockets l3 and E9 is provided with an internalkeyway 8t, and the shaft Ell-with the elongated keyway 85, wherein thekey 86 is slidably retained. Key 86 comprises the end projection 87,adapted to selectively engage one or the other of the keyways 8d ofsprockets l3 and ill.

The other end of key 86 is retained by the sliding collar which isoperatively the yoke 35, pivotally mounted on bolt 9% and sparable bymeans of the handle 92 extending from said yoke. It will be apparentthat by means of the handle 92, acting through yoke t9 and collar 88,the key 86 may be controllably positioned, per- Such adjustmentcontinues promitting selective engagement of the key projection 8? withthe key-way 84 of either of the sprockets l8 and 19. The sprocket notengaged, of course, runs free. By this means the shaft 76 and theassociated feed rolls may be driven by shaft 6? alternatively throughsprocket 78 or through sprocket 19.

The shaft it turns the lower feed roll it of stand 38, and by means ofthe associated gear 93 (Figure 11) and the meshing gear Si fixed to theupper feed roll effects contra-rotation of the roll pair. The shaft '56also drives the feed roll pair of stand it, by means of the pulley ea,fired to the end of shaft 15 opposite th transmission "fl, andoperatively engaged by the belt 95 to the variable speed pulley 91,mounted on the shaft d8 of the lower feed roll of stand 4E. The belt 95also engages the idler pulley 98, mounted on the machine frame. Thevariable speed pulley 9? may be of the typ variable in effectiv pitchdiameter in accordance with the tension of the engaging belt, controlledas by the positioning of idler pulley 99, but is more conveniently ofthe type variable in effective pitch diameter by adjustment of ahandwheel, such as handwheel 198. The upper and lower feed rolls ofstand 49 are linked in contra-rotating relationship by meshing gears,similarly to the first feed roll pair.

By the mechanism above described, the feed roll pairs are operatedintermittently, in unison, each cycle of operation effecting advance ofthe stock a distance corresponding to a single bag length. The stockadvance, or bag length, be varied over a wide range, merely by adjustingscrew 58, to suitably position the slide 5?. Since the lengths of screw58 and rack 53 are necessarily limited, the range of bag lengths whichthe machine is capable of producing is greatly extended by thetransmission l'a'. For example, the smaller sprocket 78 may be so sizedas to permit adjustment of the machine by the slide to a bag lengthranging from 1 to 18 inches, and sprocket 19 selected to correspond to abag length of from 2 to 36 inches. Obviously, the fineness of adjustmenteifected by the screw 53 is correspondingly greater when the smallersprocket it is engaged. By means of the transmission. cl, then, themachine may be shifted from a mod erate range of bag lengthadjustability, with very fine adjustment over that range, to a greatlyextended range of adjustability, when necessitated by the requirementsof the work on hand.

Due to the natural stretch of the stock and elongation thereof incidentto the heat sealing operation, which is performed intermediate the feedroll stands, to maintain the desired tension between the feed rollstands it is essential that the stock advance of the second feed rollpair exceed slightly that of the first pair. Since 1 e feed roll pairsoperate in unison, or concurrently, to attain this end it is necessarythat the pe ripheral speed of the second feed roll pair exceed that ofthe first. The peripheral speed diffcrential is effected by the variablespeed pulley Eel, and may be adjusted thereby as required. Propertensioning of the stock during and immediate- 'ly following the heatsealing operation is an important feature of the present invention, aswill presently be more fully apparent.

The facilitate initial threading of stock therethrough, means areprovided to lift the upper roll of each feed roll pair, against thepressure of the springs '15. In the case of stand 33, the treadle W2 isprovided, pivotally fixed to one of the legs H. Treadle m2, actingthrough the rod or cable N13, is adapted. to displace the lever it i(see Figure 18), thereby raising the fork member I relative to the lowerfeed roll 14, and with. the fork member the upper feed roll Me. In thecase of stand 40 (Figure 19) the upper feed roll. shaft 98a is engagedby one end of a triangular: pivot block I05, pivotally mounted on thestud. I08. The opposite end of the pivot block is engaged by theeccentric cam I01, mounted on stubshaft I08. The stub shaft andassociated cam. may be rotated by the handle I35 extendingtherefrom,causing the cam to depress the ad-- jacent end of the pivot block to thedotted lineposition shown, thereby raising the opposite end of the pivotblock and with it the upper feed roll. shaft 98a. Upon release of thehandle I39, the: spring I5 returns th upper feed roll to pressure:engagement with the lower feed roll.

The drive shaft 54 drives not only the stock feeding mechanism, as abovedescribed, but also, by means of the cams H0, III and H2, the heatsealer 39, the wiper mechanism associated with the heat sealer, and thecutter 42, respectively, all in proper coordination. After passagethrough. th first feed roll pair, the stock next passes to) the heatsealer 39.

The heat sealer (Figures 13 and 14) comprises spaced guideways extendingupwardly from the frame sides, each composed of two spaced verticalmembers H4, joined at their upper end by the I-shaped top member H5. Theoperative elements of the heat sealer are the fixed upper sealing memberI I6 and the reciprocable lower sealing member I I1, disposed with theblade portions H8 thereof in opposed relationship. The sealing membersare desirably of aluminum, annealed. and stress relieved so that themachined and polished sealing faces of the blade portions remain flatand parallel at sealing temperatures. At the bottom of slots H9, thetubular resistance heating elements I20 extend the length of the sealingmembers, and are secured by retainer bars I22. The slot H9 of the uppersealing member includes also the bulb type thermostatic element I23.

It has been found that the temperature of the sealing faces of the bladeportions H8 is maintained most nearly constant by the employment ofsealing members of relatively great mass as compared to the area of thesealing faces thereof. For example, by employing sealing members of 2 /2inches diameter and sealing faces oneeighth of an inch wide, it has beenfound that the temperature of the sealing faces is easily controlled toa range of 3 F. or less. Current to the heating elements I20 is suppliedthrough the wires I24, and controlled by switch I25, convenientlylocated on the table section 28 (see Figure 2). Adjacent switch I25 is acontrol dial I26, whereby the operative temperature of the controlelement may be selected, and, if desired, a pilot light I21 to indicatewhen current is flowing to the heating elements. The thermostaticcontrol element I23 may be of any conventional type operative to makeand break a circuit in response to changes in temperature.

The upper sealing member H6 is rigidly mounted below top member H5,desirably by means of a plurality of bolts I28, extending through thetop member and threaded into insulating blocks I29, which are in turnsuitably secured to the retainer bar I22 of the member I I6, as by thescrews I30. It will be noted that in the case of the outer bolts I28,the passage therefor through top member H5 is oversized, to accommodateexpansion and contraction of the sealing member relative to its center.

Below the upper sealing member, the guideways formed by the verticalmembers H4 retain and guide the reciprocating carriage I32. In the uppersurface of carriage I32 are provided a plurality of recesses I33,wherein are contained the coil springs I34. The support member I3I issimilarly retained and guided by said guideways, and supported above thecarriage I32 by the springs I34. Bolts I35, extending through thecarriage and threaded into the support member, limit the spacing betweenthe carriage and the support member. The lower sealing member H1 ismounted above support member I3I in opposed relationship to the uppersealing member I I5, by means of the bolts I31, insulating blocks I29,and screws I30, in a manner similar to the mounting of the upper sealingmember.

The approach of the blade portions H8 of the lower and upper sealingmembers is limited by the stop rods I38, one of which is providedbetween each pair of vertical members H4. The stop rods are threadablyengaged to the top member I I5 and extend downwardly therefrom, withtheir ends in spaced opposition to the stops I39, fixed to the supportmember I3I between the vertical members I I4 and extending upwardlytherefrom. Each of the stop rods I38 is provided at its upper end with ahandwheel I40, by means of which the operative ends of the stop rods maybe adjustably positioned.

The reciprocation of carriage I32, the support member I3I, and the lowersealing member H1 is effected by cam H0 mounted on the drive shaft 54.The cam H0 is engaged by cam follower I42, guided by the pivot arm I43depending from the frame II, and urged into contact with the cam by thespring I44 enclosing push rod I45. The push rod I45 by means of link armI40 (Figure 13) is adapted to impart rocking motion to the rock shaftI41, which motion is transmitted by the arm I48 and the link I49 to theyoke I50, suitably bolted to and extending downwardly from the carriageI32. By this means, it will be readily seen, motion of the cam followerI42 inwardly and outwardly relative to drive shaft 54 effectsreciprocation of the lower sealing member II'I toward and away from theupper sealing member H6. The details of the cam H0 are shown in Figure5, wherein it will be seen that the cam comprises a high operativesurface I52 of considerable angular extent, and a lower inoperativesurface I53. With the cam follower I42 in contact with surface I53, thespring I44 effects retraction of the lower sealing member II! to theposition shown in Figure 13. As the cam H0 rotates, the cam follower isforced outwardly from the drive shaft 54, thereby displacing push rodI45 and raising the sealing member upwardly toward the upper sealingmember H6. When the cam follower I42 is engaged by the cam surface I52,the lower sealing member is at the upper end of its travel, in spacedadjacency to the upper sealing member.

The heat sealer mechanism above described has been found to beparticularly effective in the intermittent heat sealing of polyethyleneand polyvinylidene chloride stock. Such stock is particularly liable todestruction by the application of pressure members with excessivetemperature and pressure. By means of the handwheels I40, the stop rodsI38 are adjusted to limit the approach of the lower blade portion to theupper blade portion, to a finite value less than the original thicknessof the stock being operated upon. When the lower blade portion H8engages the stock, it exerts only the pressure transmitted by thesprings I 44, and as the lower blade portion compresses the stock, thepressure exerted remains substantially constant, by virtue of theresilient mounting of the blade member. Compression of the stock betweenthe blade members is limited by the stop rods I38, which, when engagedby the stops I39, prevent further approach of the lower blade portion tothe upper blade portion, and limit the action of said blade portions forthe remainder of their cycle of operation to heat transfer to the stockengaged therebetween, thereby positively preventing severing of thestock material. By the use of a plurality of transversely spaced springsI44, uniform pressure across the width of the stock strip is insured.Further, the provision of a stop rod I38 at each end of the heat sealerprovides for differential adjustment of the maximum approach position ofthe ends of the lower sealing member, thereby providing for satisfactoryheat sealing of flattened tubular stock which may be somewhat wedgeshaped in cross section, without unduly compressing the thicker edgeportion thereof. The combination of the resilient support for the lowersealing member and the stop rods therefor affords satisfactory heatsealing of flattened tubular material comprising side tucks, whereinsuch material is of four wall thicknesses adjacent the edges thereof andof but two wall thicknesses in the center, the blades compressing thetucked portions of the stock sufiiciently to engage and heat seal thecentral portion of the stock, but being prevented from severing anyportion of said stock by the stop rods I38. The spring pressure exertedby the lower sealing member on the stock may be altered, obviously, bysuitably selecting or replacing the springs I44, and may moreconveniently be adjusted within a small range by adjusting the length ofthe push rod I45.

The cam I I (I is angularly positioned on the drive shaft 54 relative tothe slide carrier 55 and its associated stock feeding mechanism so as toeffect elevation of the lower sealing member Ill into operative positionbetween periods of stock advance, and the operative surface I52 of thecam is sufliciently long to effect engagement of the sealing members forsubstantially the entire time period between cycles of stock advance.The long period of the heat sealing step is an important feature of theinvention, as will more fully appear in the description of the operationof the machine.

The upper sealing member H6 is positioned somewhat above the normal pathof the stock I l, so that the stock is displaced upwardly by the lowersealing member as it moves into sealing engagement with the uppermember. The sealing members are desirably formed of metal, preferablyaluminum, and some thermoplastic stock materials, notably polyethyleneand polyvinylidene chloride, exhibit a decided tendency to stick to theblade portions thereof, especially to the stationary upper blade. At thetermination of the heat sealing operation, advance of the stock by thefeed rolls tends to pull the heat sealed area away from the bladeportions. The separation of the stock is facilitated by the provision ofthe pair of vertically spaced breaker bars I54, extending across thestock Path a short distance 10 beyond the point of heat sealing,conveniently between the trailing pair of vertical members I I d. Thebreaker bars have the effect of increasing the angularity with which thestock is stripped from the blade portions, thereby materially assistingthe stripping.

It has been found that sticking of the stock, especially polyethylene,to the metal sealing members may be greatly diminished by interpositionof 2. him of silicone resin therebetween. The resin is most convenientlyapplied to the blade portions of the sealing members, and the filmperiodically replenished. To this end, a spaced pair of intermittentlyoperated wiper blades I55, substantially coextensive in length with theblade portions H3, are mounted between the leading pair of verticalmembers II of the heat sealer. As is apparent in Figure 13, the guides I56 are mounted inside said vertical members, and slidably retain the endplates I57. The wiper blades I55 extend between said end plates, and arecovered by a layer of suitable absorbent material, such as felt. The endplates I5? and the associated wiper blades are reciprocated within theguides I 55 by the link I58, the guides being positioned and adapted toefiect wiping contact of the wiper blades with the blade portions of thesealing members at one end of the wiper blade traverse.

The reciprocation of the sealer blades is eftested and suitablycoordinated by the cam III mounted on the drive shaft 54. The cam II Iis engaged by cam follower I 55, urged into contact with the cam by thespring I62} enclosing push rod I 62. The push rod I 62 is operativelyconnected to the arm I63, by means of which the rock shaft I54 and armI55 are reciprocated. The reciprocation of arm I65 is transmitted bylink I 53 to the wiper blade assembly, which is caused thereby toreciprocate between the position shown in Figure 13 and a positionintermediate the sealing members, in which latter position the wipersengage the sealing member blade portions. The contour of cam I I I isshown in Figure 4, wherein it will be seen that the cam is of uniformdiameter except for the depression I56. When the cam follower Ifis ridesupon the uniform surface of the cam, the wiper blades remain in theirretracted, in operative position. When, however, the cam follower entersthe depression Ififi, the push rod I52 is displaced by the action ofspring H55 in conformity with the movement of the cam follower towardthe drive shaft 54, thereby cansing displacement of the wipers intooperative wiping engagement with the blade portions of the sealingmembers. The cam III is positioned on the drive shaft 54 to effectoperation of the wiper blade assembly when the sealing members are inretracted, inoperative position. The absorbent covering of the wiperblades is perie odically saturated with a suitable silicone resincomposition, one such being that known as D C Mold Release Emulsion #35,a water-silicone emulsion manufactured by the Dow-Corning Corporation ofMidland, Michigan.

From the heat sealer 3,9, the stock advances to feed roll stand All, andthen to the cutter mechanism 42 associated therewith. The cutter 42(Figure 17) comprises the stationary blade I57! and the movable blade I68 reciprocably mounted relative thereto. The blade IE3 is mountedbetween the blade members I69 by means of pins I15. By means of theoutwardly extending arm I72 and the tension spring I73, extending fromthe outer end of said arm to an extension of the machine frame, thecutting edge of the blade I68 is constantly urged toward the cuttingedge of blade I61, the blade I68 tending to rotate about the pins I10.The cutting edge of the upper blade is desirably ground at a slightangle, to effect a shearing action between the blades. Blade members I69are flexibly connected to the roll stand 40 by the guide arms I14,pivotally connected to the upper ends of said roll stand.

The movable upper cutting blade IE8 is reciprocated and suitablycoordinated by rotation of the cam II2 mounted on the drive shaft 54.The cam H2 is engaged by cam follower I15, and the push rod I18 is urgedby the spring I11 toward the drive shaft in accordance with the movementof the cam follower. The movement of push rod I18 is transmitted througha suitable mechanical linkage to the rod I18 and thence through arm I19to the rock shaft I80. The rock shaft I80 effects angular reciprocationof the arm I82 extending therefrom, by means of which the blade membersI68 and the associated cutting blade I58 are reciprocated in asubstantially vertical plane. The contour of the cam H2 is shown inFigure 6, wherein it will be seen that the cam is of uniform radiusexcept for the depression I83. When the cam follower I15 rides upon theuniform outer surface of the cam II2, the cutting blades are maintainedin spaced, inoperative position. When the cam follower enters thedepression I83, push rod I16 and rod I18 are displaced in the directionof the drive shaft 54, thereby effecting displacement of the blade I68downwardly into cutting engagement with the stationary blade I81. Thecam H2 is positioned on the drive shaft 54 to efiect a cutting operationbetween periods of stock advance, or in other words, while the stock isat rest. By means of the cams IIG, III and H2, then, it will be seen,the other intermittently operated mechanisms of the machine are properlycoordinated with the feed roll drive and the stepby-step advance of thestock achieved thereby. In other words, the feed roll pairsintermittently advance the stock a desired length, the length of onebag, and the heat sealer and cut ter function between the periods ofstock advance, when the stock is at rest. The wiper mechanism is timedto function when the heat sealer is inoperative, at which time, ofcourse, the stock is being advanced.

A difficult problem involved in the processing of polyethylene stock isthe accumulation on the surface thereof of static electrical charges.Once the stock is severed into individual bag lengths, control thereofis extremely difficult, and it is an outstanding feature of the presentinvention that the cutting operation is the final step. Even so, thesevered end of the elongated stock strip is diflicult to control when abag length is severed therefrom, and to obviate this difficulty it hasbeen found desirable to guide the stock through the second pair of feedrolls to the cutter in a positively controlled manner. This is attainedby the provision of a pair of spaced guide grids (see Figure 1'1)comprising the end bars I34 positioned transversely of the stock pathand suitably secured to the frame of the machine, and a plurality ofspaced guide rods or wires I85 extending between said end bars. Theguide grids are positioned and adapted to guide and contain the stock inits passage feed rolls of stand 40 substantially to the cutter. The feedrolls of stand 40 are provided with a plurality of annular grooves I88,of suitable width and depth and properly spaced to accommodate the guidewires I of the guide grids. Upon the severing of a bag length therefromby the cutter, the outer end of the stock grip is prevented by means ofthe guide grids from wrapping around the feed rolls of stand 40, orbecoming otherwise displaced from the stock path under the influence ofstatic electrical charges thereon.

To facilitate handling and stacking of the finished bags, a static barindicated generally as I81 is positioned adjacent the stock pathimmediately beyond the cutter mechanism. The static bar I81, best shownin Figure 17, is a conventional element comprising the generallycylindrical outer case I88 and the central rod I89 concentricallyenclosed thereby and suitably insulated therefrom. The case I88comprises a plurality of openings I90, and the central rod I89 aplurality of pointed projections I92 extending outwardly through saidopenings. As will be understood, the outer case I88 is customarilygrounded, and the central rod I88 subjected intermittently to current ofextremely high voltage, in the neighbourhood of 50,000 volts. The staticbar functions to periodically discharge electrons from the pointedprojections I92, they functioning as ionizing foci in a type of coronadischarge. The effect of the discharge is the electron bombardment ofthe adjacent surface of the stock, which serves to effectively disruptor neutralize the static charges on the stock. The high tension currentfor the operation of the static bar may be supplied from the source ofpower utilized to drive the motor 64, through transformer unit I93,conveniently mounted on the side of the machine frame.

The finished bags as received by receiving tray stacked against the stopI95 adjustably fixed to one side of the tray, as by the wing nut I96. Toreceive bags of greater length than can be accommodated by the tray 63,the tray extension I91 i provided, and at the end thereof the stop I88.The tray extension and associated stop are slidably retained in theguides I99 extending below the tray 43, and may be adjusted relativethereto and locked at any desired position by means of the wing nut 200.Obviously, to employ the tray extension and the stop I88, it isnecessary to remove the stop member I86 from the tray. The tray assemblyis pivotally secured to the frame at a point adjacent the cuttermechanism, and is angularly adjustable relative thereto by means of theextension rod ZilI extending from the outer end of the tray to a bracemember of the frame, as shown in Figure 1. It will be apparent that thereceiving tray arrangement may be replaced by a suitable conveyor, ifdesired, to convey the finished bags to a filling mechanism, or the bagmaking machine may be directly connected to suitable bag filling means.

As previously indicated, the periodic advance of the stock correspondsin extent to the desired bag length. The stock being tubular, each heatseal effected by the heat sealer is intended to serve as the bottomclosure of an individual bag. The stock length between the heat sealerand the cutter is so adjusted that the stock is severed immediatelyadjacent the points of heat seal, so that the action of the cutter is toseparate the closed bottom end of one bag from the open top end ofthrough the severed by the cutter are 13, and, as issued, are

the next. It is obvious, therefore, that proper registration of thecutter and the heat sealer relative to the stock must be maintained. Thestock length between the heat sealer and the cutter must at all times besubstantially equal to a whole number of bag lengths, and this extendedlength is necessarily variable to adapt the machine for fabricating bagsof diiferent lengths. To effect this adjustability and maintainregistration the roll spacer set, indicated generally as 202, i providedintermediate the heat sealer and the second feed roll pair. The rollspacer set comprises a pair of vertical guide members 203' extendingupwardly from the machine frame, and joined at their upper ends by crossmember 204. On either side of the vertical guides and rotatablysupported thereby is a stationary roller 205. As best shown in Figures15 and 16, the vertical guides 203 slidably retain bushings 285, betweenwhich the movable roller 2G1 is suitably journalled. The bushing 2% arejoined by the cross piece 208, suitably fixed, as by block 289, to theadjusting screw 2H The adjusting screw 2H] is threaded through the crossmember 204 and extends upwardly to an operating handle 2I I, suitablyaffixed to the end thereof. The lock nut 2I2 is desirably provided onthe adjusting screw 2H1 above the cros member 204, and may convenientlycomprise the operating arm 2I3 extending therefrom. It will be readilyunderstood that upon loosening the lock nut 2 I2 and rotating theadjusting screw 21:; by means of its operating handle 2, the position ofthe cross piece 203 and the movable roller 201 associated therewith maybe vertically adjusted over a considerable distance, and then locked inthe desired position. The stock is arranged to pass under the firstroller 2%, thence over the movable roller 201, and then under the otherfixed roller 205. By suitably adjusting the position of the movableroller 2831 relative to the fixed rollers, then, the stock lengthbetween the heat sealer and the cutter may be varied as desired.

The electrical system of the machine is relatively simple, and isdiagrammatically illustrated in Figure 21. As shown, the entire machineis powered by a single source of power, 115 volts A. C. beingsatisfactory, and a single circuit employed to power the motor 44 andthe transformer unit 1193 of the static bar I81. This circuit iscontrolled by main switch 2 I4, conveniently mounted on the side of theframe, and an auxiliary switch 2H5 is provided at the delivery end ofthe machine, permitting the operator to stop and start the motor 44 fromthat position. A second circuit powers the heating elements I20,controlled by the switch I25, and the thermostatic control element 23 incircuit therewith.

Operation of the machine will now be described in detail. A stock rollof suitable width, as determined by the bag width desired, and wallthickness is mounted on one of the spindles l2, and roughly alignedthereon by means of positioning cones It. The spindle is then mounted onthe frame and finally aligned by means of the screws 15. The end of thestock is then passed under the guide rods 2|, over the guide roll 22',about the guide roll 26 and over the guide rolls 21 to the table section28, in the manner previously described. The stock end is next threadedunder the control bars 31, through the first feed roll pair, through thewipers and sealing members of the heat sealer, under the firststationary roller 2% of the roll spacer set, over the movable roller-2m,under the second stationinterior surfaces of the stock ary' roller 2B5and thence through the guide grids and the second feed roller pair tothe cutter. Threading of the stock through the first feed roll pair isfacilitated by the treadle Hi2, by means of which the upper feed roll islifted, and similarly through the second feed roll pair by operation ofhandle I09.

By means of the slot 59 of screw 58, whereby the slide 51 is properlypositioned, and the selection of the desired drive ratio of thetransmission W, as controlled by the handle 92, the machine is adjustedfor the desired bag length. By means of switch I25, the heating elements223 of the heat sealer are energized and allowed to come up totemperature, and the control dial 626 set to controllably determine andmaintain the temperature of the sealing members through theinstrumentality of the thermostatic control element I23. By means ofoperating handle 2 of the roll spacer set, the extended stock length isadjusted to a multiple of the desired bag length.

The motor it may now be started by means of main switch 2ft, whereuponthe stock is intermittently advanced by the feed roll pairs. The stockadvances one bag length and stops, whereupon the heat sealer functionsto effect a transverse heat seal across the stock strip. At the sametime, the cutter functions to sever a bag length from the stool; strip.The sealing elements and cutter blades then separate, whereupon the feedroll pairs advance the stock another bag length, beginning a new cycleof operation. The sealed and severed bags are delivered directly by thecutter into the receiving tray, in stacked arrangement, or, aspreviously indicated, may be delivered to a conveyor, or directly tofilling mechanism or to shipping cartons.

The desired registry of the heat sealing and cutting operations, wherebythe stock is severed immediately adjacent the heat seals, may bemaintained by adjustment of the roll spacer set while the machine isoperating. Similarly, necessary adjustments of the bag lengthnecessitated by variable stock elongation or other conditions may beeffected by adjustment of slide 5? by means of the handle 13, alsowithout interrupting the operation of the machine. The spacing betweenthe sealing members at their point of nearest approach may be suitablyselected by means of the stop rods I33, in accordance with the originalthickness of the stock, the type of stock material being fabricated, andother variables, and if the thickness of the stock is not uniform acrossits width, differential adjustment may be effected thereby.

The control bars '31 facilitate the stock feed by flattening and guidingthe stock, and also serve to prevent fold-over and other undesirablebehavior of poor stock. In the event the are found to be slightlyblocked, making opening of the finished bags difiicult, a bubble of airor other fluid may be inserted into the interior of the stock andretained between the control bars. This is simply performed bypuncturing one wall of the stock intermediate said control bars,inserting the desired fluid, and then sealing the puncture, as with apiece of tape. In this manner the stool: is opened interiorly in passagethrough the machine, and the finished bags are assured to be freelyopening.

The functioning of the viously indicated, is highly heat sealer, aprecritica-l. Polyethyl- "ene stock exhibits a sharply defined meltingpoint range, usually within the range of from 218 to 220 F. Infabricating polyethylene material, the heat sealer has been found tofunction best if the temperature of the sealing members thereof ismaintained at a temperature slightly below the melting point range ofthe stock, temperatures within the range of from 210 to 215 F. havingbeen found to be especially suitable. The melting point range ofpolyvinylidene chloride material is similarly sharply defined, in theneighbourhood of 270 F., and a sealing member temperature slightly belowthe melting point has been found to be similarly effective insatisfactorily heat sealing this material. In employing sealingtemperatures below the melting point range of the stock, momentaryengagement of the stock by the sealing members has been foundinsufficient to effect a satisfactory seal, even with high pressure. Forthis reason, the cam H is so designed and the speed of the machineaccordingly coordinated as to effect sealing contact of the stock by thesealing members for a time period of from 0.05 to 1.0 sec ond,preferably between 0.1 and 0.5 second. The sealing time period and thesealing temperatures above specified, combined with the uniformity ofpressure application throughout the heat sealing operation, which is aninherent characteristic of the resiliently mounted sealing member,together have been found to effect excellent fluidtight seals, ofuniformly good appearance. That is, the heat sealed stripe is smooth,fiat and uniform, and the adjacent areas of the stock not deformed bywrinkles, undulations or the like.

In order to preserve the uniformly excellent appearance of the seals inthe finished bags, it has been found desirable to maintain the stockunder tension until the seals have cooled. This effect is inherent inthe embodiment described, wherein the stock traverses a considerabledistance, corresponding to several bag lengths and cycles of operation,between the heat sealer and the second feed roll stand. As previouslystated, the second feed roll stand is operated at greater peripherealspeed than is the first feed roll stand, thereby effecting a slightlygreater stock advance per cycle of operation, whereby stretch of thematerial and elongation thereof incident to the heat sealing operationare absorbed, and the desired tension maintained in the stock stripbetween the first and second feed roll stands. The operator, of course,may adjust the speed differential between the feed roll stands, as maybe necessary to maintain proper tension, .by means of the variable speedpulley 99. In fabricating polyvinylidene chloride stock, ten- 'sioningof the material during cooling of the heat seals is especiallydesirable, since under the influence of heat the molecular orientationof this material tends to become disturbed, causing curling andwrinkling of the extruded stock material.

When satisfactory adjustments have been made and perfect bags of thedesired length are being uniformly produced, the operation of themachine may be speeded up by movement of the motor 44, to increase theeffective pitch diameter of the variable speed pulley thereof, or in thecase of a variable speed motor, merely by suitable control. Operated inthis manner, the machine is capable of producing continuously from 2,000to 4,000 bags per hour, the production rate varying more or lessinversely with the length of the bags being produced.

It willthus be seen, that there has been provided by this invention amachine by which the various objects hereinbefore set forth, togetherwith many practical advantages, are successfully achieved. As variouspossible embodiments may be made of the mechanical features of the aboveinvention, all without departing from the scope thereof, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

This application is a division of application Serial No. 82,934, filedMarch 23, 1949.

We claim:

1. Apparatus for making bags from tubular thermoplastic stock comprisinga first pair of feed rolls, a second pair of feed rolls, means forintermittently driving said feed roll pairs in unison, intermittentlyoperated sealing means positioned intermediate said feed roil pairs,intermittentlv operated cutting means positioned beyond said second feedroll pair, means coordinating the operation of said feed roll pairs,said sealing means and said cutting means whereby said sealing means andsaid cutting means operate between intervals of feed roll operation, andmeans for adjusting the stock length between said sealing means and saidcutting means.

2. Apparatus for making bags from tubular thermoplastic stockcomprising: a first pair of feed rolls; a second pair of feed rolls;means for intermittently driving said feed roll pairs in unison;intermittently operated heat sealing means positioned intermediate saidfeed roll pairs, said heat sealing means including a pair of spacedparallel guideways, a fixed sealing member rigidly mounted with respectto said guideways, a reciprocating carriage slidably retained by saidguideways in opposed relationship to said fixed sealing member, amovable sealing member resiliently supported by said carriage in spacedadjacency to said fixed sealing member, and means for controllablyheating said sealing members; intermittently operated cutting meanspositioned beyond said second feed roll pair; and means coordinating theoperation of said feed roll pairs, said heat sealing means and saidcutting means whereby said heat sealing means and said cutting meansoperate between intervals of feed roll operation.

3. Apparatus for making bags from tubular thermoplastic stock comprisinga first pair of feed rolls, a second pair of feed rolls, means forintermittently driving said feed roll pairs in unison at differentperipheral speeds, means for continuously varying the peripheral speeddifferential between said feed roll pairs, intermittently operated heatsealing means positioned intermediate said feed roll pairs,intermittently operated cutting means positioned beyond said second feedroll pair, and means coordinating the operation of said feed roll pairs,said heat sealing means and said cutting means whereby said heat sealingmeans and said cutting means operate between intervals of feed rolloperation.

4. Apparatus according to claim 2, wherein said heat sealing meansincludes adjustable stop means associated with each of the guideways tocontrollably and differentially limit the approach of the movablesealing member to the fixed sealing member.

5. Apparatus for making bags from tubular thermoplastic stock comprisinga first pair of feed rolls, a second pair of feed rolls, means forintermittently driving said feed roll pairs in unison, intermittentlyoperated heat sealing means positioned intermediate said feed rollpairs, Wiper means adapted to engage said heat sealing means ininoperative position, intermittently operated cutting means positionedbeyond said second feed roll pair, and coordinating means effective tooperate said heat sealing means and said cutting means when said feedroll pairs are at rest and to operate said wiper means when said heatsealing means is inoperative.

6. Apparatus for making bags from tubular thermoplastic stock comprisinga first pair of feed rolls for advancing said stock, a second pair offeed rolls for advancing said stock, means for intermittently drivingsaid feed roll pairs in unison at different peripheral speeds, theperipheral speed of said second pair being the greater, intermittentlyoperated sealing bars positioned in.- termediate said feed roll pairsadjacent the of said stock and transverse thereto, intermittentlyoperated cutting means positioned beyond said second feed roll pairadjacent the path of said stock and transverse thereto, coordinatingmeans effective to operate said sealing means and said cutting meanswhen said feed roll pairs are at rest, three guide rollers positionedintermediate said sealing bars and said cutting means along the path ofsaid stock, and means for adjusting the position of the center rollerrelative to the other two of said rollers, whereby the operation of saidsealing bars and said cutting means may be maintained in predeterminedregistry on said stock.

7. Apparatus for making bags from tubular thermoplastic stock comprisinga first pair of feed rolls for advancing said stock, a second pair offeed rolls for advancing said stock, means for intermittently drivingsaid feed roll pairs in unison at different peripheral speeds, means forcontinuously varying the peripheral speed differential between said rollpairs, intermittently operated heat sealing bars positioned intermediatesaid feed roll pairs adjacent the path of said stock and transversethereto, reciprocating wiper means adapted to engage said sealing barsin inoperative position, intermittently operated cutting meanspositioned beyond said second feed roll pair adjacent the path of saidstock and transverse thereto, and coordinating means effective tooperate said heat sealing bars and said cutting means when said feedroll pairs are at rest and to operate said Wiper means when said heatsealing bars are inoperative.

8. Heat and pressure sealing mechanism including a fixed sealing member,a reciprocating carriage mounted in opposed relationship to said fixedsealing member, a movable sealing member resiliently supported by saidcarriage in spaced adjacency to said fixed sealing member, means forheating said sealing members, and means for reciprocating said carriagewhereby said movable sealing member is periodically brought intooperative sealing relationship with said fixed sealing member.

9. Heat and pressure sealing mechanism including a pair of spaced,parallel guideways, a fixed sealing member rigidly mounted with respectto said guideways, a reciprocating carriage slidably retained by saidguideways in opposed relationship to said fixed sealing member, amovable sealing member resiliently supported by said carriage in spacedadjacency to said fixed sealing member, means for controllably heatingsaid sealing members, and means for reciprocating said carriage wherebysaid movable sealing me;

path

i 18 her is periodically brought into operative sealing relationshipwith said fixed sealing member.

10. Mechanism according to claim 9, wherein said sealing members are ofgreat mass relative to the effective sealing area thereof.

11. Heat and pressure sealing mechanism including a pair of spaced,parallel guideways, a fixed sealing member rigidly mounted with respectto said guideways, a reciprocating carriage slidably retained by saidguideways in opposed relationship to said fixed sealing member, sprinmeans extending from said carriage, a movable sealing member retained bysaid guideways and resiliently supported by said spring means in spacedadjacency to said fixed sealing member, means for controllably heatingsaid sealing members, means for reciprocating said carriage whereby saidmovable sealing member is periodically brought into operative sealingrelationship with said fixed sealing member, and adjustable stop meansto limit the approach of said movable sealing member to said fixedsealing member.

12. Heat and pressure sealing mechanism including a pair of spaced,parallel guideways, a fixed sealing member rigidly mounted with respectto said guideways, a reciprocating carriage slidably retained by saidguideways in opposed relationship to said fixed sealing member, aplurality of spaced spring means extending from said carriage, a movablesealing member retained by said guideways and resiliently supported bysaid spring means in spaced adjacency to said fixed sealing member,means for controllably heating said sealin members, means forreciproeating said carriage whereby said movable sealing member isperiodically brought into operative sealing relationship with said fixedsealing member, and adjustable stop means associated with each of saidguideways to controllably and differentially limit the approach of saidmovable sealing member to said fixed sealing member.

13. Heat and pressure sealing mechanism including a pair of spaced,parallel guideways, a fixed sealing member rigidly mounted with respectto said guideways, a reciprocating carriage slidably retained by saidguideways in opposed relationship to said fixed sealing member, amovable sealing member retained by said guideways and resilientlysupported by said carriage in spaced adjacency to said fixed sealingmember, means for reciprocating said carriage whereby said movablesealing member is periodically brought into operative sealingrelationship with said fixed sealing member, adjustable stop means tolimit the approach of said movable sealing member to said fixed sealingmember, Wiper blades mounted for lateral reciprocation between saidguideways relative to said sealing members, means for reciprocating saidwiper blades, and means coordinating the reciprocation of said wiperblades and said movable sealing member to effect operation of said wiperblades when said sealing members are in spaced, inoperative position.

14. Apparatus for making bags from tubular thermoplastic stockcomprising: a first pair of feed rolls, a second pair of feed rolls,means for intermittently driving said feed roll pairs in unison,intermittently operated sealing means positioned intermediate said feedroll pairs, intermittently operated cutting means positioned beyond saidsecond feed roll pair, means coordinating the operation of said feedroll pairs, said sealing means and said cutting means to cause operationof said sealing means and said cutting means between intervals of feedroll operation, and spaced guide grids positioned and adapted to guidethe stock through said second pair of feed rolls to said cutting means,said second pair of said rolls being circumferentially grooved toaccommodate said guide grids.

15. In apparatus for making bags from tubular thermoplastic stock havingtransverse heat-sealing means, cutting means spaced therebeyond, meansfor advancing the stock from the sealing means to the .cutting means andmeans for intermittently operating the stock-advancing means and foroperating the sealing means and the cutting means between intervals ofstock advance, the combination of means disposed between the sealingmeans and the cutting means for adjusting the stock length therebetween.

16. The structure defined in claim 15 in which the stock lengthadjusting means includes adjustably mounted roll means for deflectingthe stock from a direct path of travel between the sealing means and thecutting means.

17. The structure definedin claim 15 in which the sealing means and thecutting means are mounted in fixed relation to each other.

18. The structure defined in claim 15 including means for operating theadjusting means during operation of the apparatus.

19. The structure defined in claim 15 in which the adjusting meansincludes a roll disposed between the sealing means and the cuttingmeans, transversely of the path of travel of the stock, and inengagement with the latter; and means mounting said rollforsubstantially translational adjusting movements to and from the planeof the stock.

20. The structure defined in claim 19 including a manually-operablecrank for operating the roll mounting means.

.21. In apparatus for making bags from tubular thermoplastic stockhaving a pair of feed rolls,

cutting means disposed substantially immedi-.

ately therebeyond, and means for intermittently operating thefeed rollpair and for operating the cutting means between intervals of feed rolloperation, the combination of spaced guide grids positioned to guide thestock through and between the rolls to the cutting means without wrap-upon the rolls; and means defining circumferential grooves in the rollsfor accommodating said guide grids.

22. Heat and pressure sealing mechanism including a rigid abutment, areciprocating carriage mounted in opposed relation to said abutment, amovable sealing member resiliently supported by said carriage in spacedadjacency to said abutment, means for heating said sealing member, andmeans for reciprocating said carriage whereby said movable sealingmember is periodically brought into operative sealing relationship withsaid abutment.

.23. The structure defined in claim 22 including adjustable stop meansto limit the approach of the sealing member to the abutment.

THEODORE W. KELLER. CHARLES W. GARVIN.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,155,614 Petskeyes et al Apr. 25, 1939 2,326,931 Dalton Aug.17, 1943 2,376,253 Humphrey May 15, 1945 2,449,972 Beach Sept. 28, 19482,467,879 Billeb Apr. 19, 1949

